How many times did you fire the brass?
Not necessarily a matter of how many times fired.......can be headspace vs. FL/Bump die setting
. That was my problem with the 220 Swift initially, little bit on the long side of SAAMI headspace (I mean not even barely measureable), and bumping the shoulder more than needed when resizing.........That's all it took, and it left me "stranded
My point is, we can fire our brass a hell uva lot and still be good to go, as long as we set up our reloading dies correctly for the rifle being shot. (factory diections are only general guides).
Not trying to imply that was the case in your situation, but something to look at nonetheless.
Best o Luck!